Varu...First off, most excellent stacking of the Flow Illustrators, how did you do that? I'd love to be able to do the same to compare different renderings.
Next, I looked
DEEPLY 
at your bit map.....and there are a shat load of pixels drifting about. No biggie, just next time, use your eraser really good. Flow Illustrator sees anything which isn't white (Really white) as solid. I use Paint to make my .bmps, there is a function there under, Image/Attributes to select B&W which I always do. That way no gray scale artifacts show up.
I have gotten really good using the Draw feature in Word to make outlines. Once you get used to it, Draw is super easy to trace out complex curves on a photograph. I can trace a car in about 7 Minutes. Then it is easy to cut & paste the drawing into paint, B&W it and tadaaa.